In a conventional brewhouse, ground malt is slurried with hot water in a mash mixer vessel which is equipped with a slow speed mixer. After a heating and hold cycle, the starches in the mash are coverted into fermentable sugars by an enzyme reaction. The converted mash is then pumped or dropped into a lauter tun which is a larger diameter vessel having a false bottom. This false bottom retains the spend grains on top of it while the wort, (extract of malt and possibly containing some cooked cereals as well) lauters (filters) through the false bottom and is collected for further processing. In addition, underdough collects under the lautering screen and must be removed by manual or automatic flushing with water. The spend grains (malt husks) are removed by automatic rakes that plow the spend grains to openings through which these spend grains fall for removal for drying or disposal as animal feed. Other devices such as wort filters are used to achieve this separation.
These are also combination mash-lauter tuns in use that combine the mashing and lautering in one vessel. However, for the small micro-breweries, it is not economical to construct the conventional lauter tun or combination mash-lauter tun because of the high cost of the equipment required to make these vessels functional.